PROVIDENCE, R.I. (AP) — The Trinity Repertory Co. is cleaning up and assessing damage after a small fire filled its historic Providence building with smoke on Monday, and officials are trying to determine whether the opening of a show scheduled for this week can go ahead.

Acting Fire Chief Michael Dillon says about 25 firefighters responded to the theater building — which is on the National Register of Historic Places — shortly after 8 p.m. Firefighters found a mattress burning on a stage in one of the theaters.

No performances were going on at the time and no one was hurt, though a small number of people in the building, including rehearsing students and security, were evacuated, according to theater spokeswoman Marilyn Busch.

Dillon said the fire was confined to the mattress and was quickly extinguished. But he said the building was filled with smoke and it took a while to clear it because there are few natural openings.

Busch said the smoke and water damage was worse than the damage from the fire.

"The major problem was the amount of smoke," she said.

The show "Social Creatures" is scheduled to open Thursday in the damaged space for a five-week run, and officials are assessing whether it will be possible for the show to go on. Cast members are already supposed to be rehearsing in the space, Busch said.

"Right now we're in the middle of cleanup," she said. "We're hoping that everything will be business as usual."

The theater had no immediate estimate on how much the damage will cost.

Dillon said the cause of the fire is under investigation.

The regional theater group was founded in 1963 and its building, the former Majestic Theatre, opened in 1917 as a vaudeville house. The building, done in the Beaux Arts style, was added to the National Register of Historic Places in 1972.

Trinity helped launch the careers of two-time Tony Award-winning actress Viola Davis and stage and screen actor Richard Jenkins.